Matrix converters can suppress harmonic current and effectively use regenerative electric power, and therefore attract attention as a new power converter. A matrix converter, for example, includes a plurality of bidirectional switches connecting respective phases of an AC source and respective phases of a load, and outputs arbitrary voltage and frequency to the load by controlling these bidirectional switches and directly switching each phase voltage of the AC source.
The matrix converter performs PWM control on the bidirectional switches and controls its conduction rate, so that a load-side voltage is typically lower than an AC-source-side voltage. However, recently, there is proposed a matrix converter that has a step-up function of causing the load-side voltage to be higher than the AC-source-side voltage.
For example, a matrix converter described in International Publication Pamphlet No. WO 2006/112275 includes reactors on respective phases of an AC source, bidirectional switches, and capacitors that connect respective phases of outputs connected to a load. The matrix converter connects two or more reactors to capacitors after short-circuiting between bidirectional-switch side terminals of the reactors by controlling the bidirectional switches. Consequently, a step-up function of causing a load-side voltage to be higher than an AC-source-side voltage is realized in the matrix converter.
In the matrix converter, it is desired to easily perform control of bidirectional switches.